Custom Point of sales Apps with data sync to Web Application

Hi Below is the summary of the requirement. 1. Mobile application with at least below listed features a. Inventory management i. Create item Code ii. Add or reduce inventory iii. View and review balance b. Point of sale invoice page i. search / Add item - with existing balance ii. Amount calculation iii. Discount files iv. Previous Purchase View c. Customer creation i. Add and update details ii. Add and update balance iii. Auto add and update balance based on sale d. Add Supplier i. Add and Update purchase ii. Add and update payments e. Summary reports f. add and update and export data using excel 2. Create a basic static Front facing website a. Feature to Sync data to the - Suggestions welcome b. Download apps feature c. register and contact page d. data structure same as apps on web e. Sync data to a web f. Sync and backup based on password g. Download app with registration code post payment h. Admin page to update data Timelines are 2 Months from the committing Be flexible to reuse open source mobile apps Target gadget is android tablet I am open to alternates and suggestions, Application should be light weight and flexible in future changes Source code should be shared with design details Regards Ajay